What does the JSONL / NDJSON Viewer do?
JSONL (also called NDJSON) stores one JSON value per line, which is common for logs and data exports. This viewer shows each line as a table row, lets you filter and search, opens any record as a tree, and highlights lines that are not valid JSON.
How to use the JSONL / NDJSON Viewer
- Paste your JSONL text or open a .jsonl, .ndjson or .log file.
- Read the Records table. Columns are detected from the most common keys.
- Filter by level (error, warn, info) or type in the filter box to search every line.
- Click a row to inspect the record as a tree. Invalid lines are marked in red with a link to fix them.
When it helps
- Reading application and server logs
- Checking an export before loading it into a database
- Finding the one malformed line in a large file
Frequently asked questions
What is the difference between JSON and JSONL?
A JSON file holds one value, usually a big array. A JSONL file holds one complete JSON value on every line, so it can be read and written one line at a time.
Are NDJSON and JSONL the same thing?
In practice, yes. Both mean newline-delimited JSON: one JSON value per line, separated by a line break.
How many lines can I open?
The viewer reads up to 200,000 lines in the browser and shows rows in pages of 1,000 so the page stays fast.
What happens to lines that are not valid JSON?
They are listed in red with the reason, skipped in exports, and each has a Fix button that sends the line to the JSON Repair tool.